Bug: destructuring + calling function with same param name as destructured var

[xaviergonz]

Bug report

Uglify version (uglifyjs -V) latest

JavaScript input

(function() {

const animReq = (data) => {
  const { newRotation, character } = data;
  console.log('')
  const rotationDuration = getRotationDuration(newRotation, character.rotation);
  console.log('')
  return rotationDuration;
}

function getRotationDuration(newRotation, oldRotation) {
  return getRotationDeltaDuration(newRotation - oldRotation);
}

function getRotationDeltaDuration(rotationDelta) {
  const durationMultiplier = Math.round(Math.abs(rotationDelta)) / 180;
  if (durationMultiplier === 0) {
    return 0;
  }
  return lerp(150, 450, durationMultiplier);
}

function lerp(v0,v1,t) {
  return v0 * (1 - t) + v1 * t;
}


animReq({
  newRotation: 10,
  character: {
    rotation: 100
  }
});

})()

The uglifyjs CLI command executed or minify() options used.

npx uglify-es --compress -- test.js

JavaScript output or error produced.

The output is the following:

!function(){var newRotation,oldRotation;(data=>{const{newRotation:newRotation,character:character}=data;console.log("");const rotationDuration=(newRotation=newRotation,oldRotation=character.rotation,function(rotationDelta){const durationMultiplier=Math.round(Math.abs(rotationDelta))/180;return 0===durationMultiplier?0:150*(1-(t=durationMultiplier))+450*t;var t}(newRotation-oldRotation));console.log("")})({newRotation:10,character:{rotation:100}})}();

The problem is with the sequences compress option, which generates this part:

const{newRotation:newRotation,character:character}=data;
...
const rotationDuration=(newRotation=newRotation,...

where newRotation=newRotation fails because newRotation is const and cannot be reassigned

[xaviergonz]

PS: if the function argument is changed to something other than the destructured var name (e.g.

const { newRotation, character } = data;
...
function getRotationDuration(newRotation2, oldRotation) {

it works since the generated expression is then newRotation2=newRotation

[kzc]

Fixed in https://www.npmjs.com/package/@fabiosantoscode/uglify-es

[xaviergonz]

There are two uglify-es packages? What's the difference?

[kzc]

https://www.npmjs.com/package/@fabiosantoscode/uglify-es is maintained.

[xaviergonz]

Sorry if this sounds like a silly question but, why aren't both packages joined then with more contributors? The latest commit to this one (I presume the official one) is only 11h old.

I ask because I'm actually using using a bundler (fusebox) that depends on this uglify-es package internally and I think the only way I could get it to work is to make a yarn alias from one to the other, which feels weird.

[kzc]

One is actively maintained and the other is not. Use whatever package you prefer.

[alexlamsl]

Fixed in #2881